Did you follow these steps to create your VM: HowTo: Install Kegbot Server on Digital Ocean
If that is the case you need to run the commands
root@my-kegbot:~# su - kegbot
kegbot@my-kegbot:~$ . kegbot-server.venv/bin/activate
(kegbot-server.venv)kegbot@my-kegbot:~$ kegbot backup